Development of a Conceptual Process for Selective CO2 Capture from Fuel Gas Streams Using [hmim][Tf2N] Ionic Liquid as a Physical Solvent

Abstract

The ionic liquid (IL) [hmim][Tf2N] was used as a physical solvent in an Aspen Plus simulation, employing the Peng–Robinson Equation of State (PR-EOS) with Boston–Mathias (BM) α-function and standard mixing rules, to develop a conceptual process for CO2 capture from a shifted (undergone the water–gas shift reaction) warm fuel gas stream produced from Pittsburgh #8 coal for a 400 MWe IGCC power plant. The physical properties of the IL, including density, viscosity, surface tension, vapor pressure, and heat capacity were obtained from literature and modeled as a function of temperature. Also, available experimental solubility values for CO2, H2, H2S, CO, and CH4 in this IL were compiled, and their binary interaction parameters (δij and lij) were optimized and correlated as functions of temperature. The Span–Wager EOS was also employed to generate CO2 solubilities in [hmim][Tf2N] at high pressures (up to 10 MPa) and temperatures (up to 510 K). The conceptual process developed consists of four adiabatic absorb...